A copper-aluminum catalyst, a preparation method, application and a regeneration method thereof

Abstract

The application provides a copper-aluminum catalyst, a preparation method, application and a regeneration method, relates to the technical field of indole synthesis, and the copper-aluminum catalyst is an oxide formed by Cu, Al and an auxiliary metal; the auxiliary metal is a divalent auxiliary metal and / or a trivalent auxiliary metal; wherein the ratio of the total moles of Cu and the divalent auxiliary metal to the total moles of Al and the trivalent auxiliary metal is 3:1~1:3, the mass content of Cu accounts for more than 60% of the total mass content of Cu and the divalent auxiliary metal, and the mass content of Al accounts for more than 80% of the total mass content of Al and the trivalent auxiliary metal. The copper-aluminum catalyst provided in the embodiment of the application has high stability and catalytic activity for synthesizing indole under high-temperature conditions, the indole yield can be kept above 50% after 200 h of reaction, the copper-aluminum catalyst can basically recover to the initial activity after being regenerated through multiple in-situ calcination, has good economy and practicability, and has a good industrial application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of synthetic indole, and particularly relates to a copper-aluminum catalyst, a preparation method, application and a regeneration method thereof. BACKGROUND

[0002] Indole is an important heterocyclic fine chemical raw material, which is widely used in the fields of medicine, pesticide, perfume, food, feed additive, dye and the like. The alcohol amine method is a method for gas-phase synthesis of indole by using aniline and ethylene glycol as raw materials under the action of a metal catalyst. The method has obvious advantages such as low raw material price, low production cost, simple operation process and no generation of inorganic salt waste harmful to the environment in the reaction, and is the most economical one among many indole synthesis methods. In the process of indole synthesis, the use of catalyst is particularly important.

[0003] At present, in the research and development of catalysts for the alcohol amine method for synthesizing indole, the use of high-pollution Pb and Cd catalysts has been eliminated; the research on noble metal and rare metal catalysts is also relatively less; among non-noble metal catalysts, copper-based catalysts have been widely studied due to their high activity and low price. However, the overall service life of the copper-based catalysts used in the alcohol amine method for synthesizing indole is not long, because the aromatic by-products N-ethyl aniline and N-acetyl aniline generated in the reaction are adsorbed on the surface of the catalyst, resulting in catalyst poisoning and deactivation. Further, in view of the catalyst poisoning and deactivation, the existing improvement method is to introduce H2 and water vapor into the system to reduce and remove the by-products as much as possible. This method has a certain effect on improving the service life of the catalyst, but the service life extended by this method is limited, and therefore its industrial applicability needs to be further improved.

[0004] Therefore, in the technical field of synthetic indole, the poor catalytic activity and stability of the copper-based catalyst for synthesizing indole have become a technical problem to be solved at present. SUMMARY

[0005] To solve the above problems, in a first aspect, the present application provides a copper-aluminum catalyst, which is an oxide formed by Cu, Al and an auxiliary metal; the auxiliary metal is a divalent auxiliary metal and / or a trivalent auxiliary metal; the divalent auxiliary metal is one or more of Mg, Zn, Ni, Ca and Co, and the trivalent auxiliary metal is one or more of Cr, Y, La and Fe.

[0006] The ratio of the total moles of the Cu and the divalent auxiliary metal to the total moles of the Al and the trivalent auxiliary metal is 3:1-1:3; the Cu accounts for more than 60 % of the total amount of substance of the Cu and the divalent auxiliary metal, and the Al accounts for more than 80 % of the total amount of substance of the Al and the trivalent auxiliary metal.

[0007] Preferably, the copper-aluminum catalyst further comprises Mg.

[0008] The ratio of the total moles of the Mg, the Cu and the divalent auxiliary metal to the total moles of the Al and the trivalent auxiliary metal is 3:1-1:3; the Mg accounts for more than 30 % of the total amount of substance of the Mg, the Cu and the divalent auxiliary metal.

[0009] Preferably, the auxiliary metal is a divalent auxiliary metal and a trivalent auxiliary metal, the divalent auxiliary metal is Ca, and the trivalent auxiliary metal is Y.

[0010] The total mole ratio of the Mg, the Cu, the divalent auxiliary metal, the Al and the trivalent auxiliary metal is 1:2; the Cu accounts for 60 % of the total amount of substance of the Mg, the Cu and the divalent auxiliary metal, the Mg accounts for 30 % of the total amount of substance of the Mg, the Cu and the divalent auxiliary metal, and the Al accounts for 90 % of the total amount of substance of the Al and the trivalent auxiliary metal.

[0011] In a second aspect, the present application provides a preparation method of the copper-aluminum catalyst used for synthesizing indole in the first aspect, and the preparation method comprises:

[0012] S1, uniformly mixing a Cu source, an Al source and an auxiliary metal source, and then placing the mixture in a ball mill jar for ball milling, and then drying the mixture after the ball milling to obtain a catalyst precursor; the auxiliary metal source is a divalent auxiliary metal source and / or a trivalent auxiliary metal source; the divalent auxiliary metal source is one or more of Mg, Zn, Ni, Ca and Co sources, and the trivalent auxiliary metal source is one or more of Cr, Y, La and Fe sources;

[0013] S2, grinding the catalyst precursor, and then placing the catalyst precursor in an air or oxygen atmosphere, and then calcining the catalyst precursor at 800-1200 ℃ for 1-6 h to obtain a copper-aluminum catalyst.

[0014] Preferably, the Cu source, the Al source and the auxiliary metal source are uniformly mixed, and the mixing comprises:

[0015] The Cu source, the Al source and the auxiliary metal source are uniformly mixed in a solvent; and the solvent is a mixture comprising polyethylene glycol.

[0016] Preferably, the Cu source is one or more of copper oxide, copper hydroxide, copper acetate, and the Al source is one or more of aluminum oxide, aluminum hydroxide, and pseudo-boehmite.

[0017] The solvent is a mixture of polyethylene glycol and deionized water in a mass ratio of 0.1-6:100.

[0018] Preferably, the ball milling process is as follows: zirconium balls with a diameter of 5-10 mm are added, and ball milling is performed at a rotation speed of 200-800 r / min for 2-15 h.

[0019] The drying process parameters are as follows: drying at a temperature of 80-150℃ for 5-24 h.

[0020] Preferably, the Mg source is one or more of magnesium oxide, magnesium hydroxide, and magnesium acetate.

[0021] In a third aspect, the present application provides a copper-aluminum catalyst for use in the one-step synthesis of indole compounds or indole derivatives by the alcohol amine method.

[0022] Preferably, the use comprises:

[0023] Aniline and ethylene glycol are directly reacted using the copper-aluminum catalyst under the conditions of hydrogen being introduced, a reaction temperature of 260-350℃, and a space velocity of 0.1-3.0 h -1 -1 The molar ratio of aniline to ethylene glycol is 1:1-9:1.

[0024] When the raw materials are N-methylaniline and ethylene glycol, N-methylindole can be obtained directly using the copper-aluminum catalyst and the process conditions; when the raw materials are N-ethylaniline and ethylene glycol, N-ethylindole can be obtained directly using the copper-aluminum catalyst and the process conditions; when the raw materials are m-methylaniline and ethylene glycol, 4-methylindole and 6-methylindole can be obtained directly using the copper-aluminum catalyst and the process conditions; when the raw materials are p-methylaniline and ethylene glycol, 5-methylindole can be obtained directly using the copper-aluminum catalyst and the process conditions; when the raw materials are aniline and glycerol, 3-methylindole can be obtained directly using the copper-aluminum catalyst and the process conditions; and when the raw materials are aniline and 1,2-propanediol, 2-methylindole can be obtained directly using the copper-aluminum catalyst and the process conditions.

[0025] ​Preferably, when the raw materials are aniline and glycerol, the molar ratio of aniline and ethylene glycol is 9:1, the reaction is directly carried out by using the copper-aluminum catalyst under the conditions of hydrogen being introduced, the reaction temperature being 260 ℃, and the space velocity being 3.0 h -1 The yield of 3-methylindole (calculated based on glycerol) is 76.4 %.

[0026] In a fourth aspect, the present application provides a regeneration method of the copper-aluminum catalyst, the copper-aluminum catalyst after being applied in the third aspect is regenerated by in-situ air roasting.

[0027] Preferably, the regeneration process of the copper-aluminum catalyst is as follows:

[0028] Air or oxygen-containing nitrogen is introduced into the reactor, and the copper-aluminum catalyst after the reaction is heated and kept warm in an in-situ manner under the conditions of a gas space velocity of 50 h -1 ~1000 h -1 The regeneration of the copper-aluminum catalyst is completed after the heating rate is 0.1 ℃ / min~0.5 ℃ / min, the temperature is increased to 200 ℃~400 ℃, and the temperature is kept for 15 h~20 h, and the regenerated copper-aluminum catalyst is used again in the reaction of synthesizing indole compounds or indole derivatives.

[0029] Compared with the prior art, the present application has the following advantages:

[0030] The present application provides a copper-aluminum catalyst, a preparation method, an application and a regeneration method thereof, relates to the technical field of synthesizing indole, and the copper-aluminum catalyst is an oxide formed by Cu, Al and an auxiliary metal; the auxiliary metal is a divalent auxiliary metal and / or a trivalent auxiliary metal; wherein the ratio of the total moles of Cu and the divalent auxiliary metal to the total moles of Al and the trivalent auxiliary metal is 3:1~1:3, the content of Cu in the total mass of Cu and the divalent auxiliary metal is more than 60 %, and the content of Al in the total mass of Al and the trivalent auxiliary metal is more than 80 %. The copper-aluminum catalyst provided in the embodiments of the present application has high stability and catalytic activity for synthesizing indole under high-temperature conditions, the yield of indole can be kept above 50 % after 200 h of reaction, the copper-aluminum catalyst can basically recover to the initial activity after being regenerated by multiple in-situ roasting, has good economy and practicability, and has a good industrial application prospect.

[0031] The copper-aluminum catalyst provided by the embodiment of the present application improves the stability and catalytic activity in the following two aspects. On the one hand, the space structure of the copper-aluminum catalyst is changed by introducing an auxiliary metal, the release rate of copper of the copper-aluminum catalyst during use is controlled, the deactivation caused by the agglomeration and sintering of the released copper is slowed down, thereby the stability and catalytic activity of the copper-aluminum catalyst are improved. On the other hand, since the copper-aluminum catalyst does not introduce a carrier, the pore structure is not complex, the specific surface area is relatively small, the adsorption of aromatic by-products is small, the poisoning and deactivation of the catalyst are reduced to a certain extent, thereby the stability and catalytic activity of the copper-aluminum catalyst are improved. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0033] Figure 1 The flow chart of the preparation method of the copper-aluminum catalyst provided by the embodiment of the present application is shown in the figure.

[0034] Figure 2 The scanning electron microscope image of the copper-magnesium-aluminum catalyst provided by the embodiment 4 of the present application is shown in the figure.

[0035] Figure 3 The pore size distribution graph of the copper-magnesium-aluminum catalyst provided by the embodiment 4 of the present application is shown in the figure. DETAILED DESCRIPTION

[0036] The following embodiments are provided to better further understand the present application, and are not limited to the best embodiments, and do not limit the content and protection scope of the present application. Any person who obtains any product same or similar to the present application under the inspiration of the present application or by combining the present application with other prior art features falls within the protection scope of the present application.

[0037] The specific experimental steps or conditions are not specified in the embodiments, and can be operated according to the conventional experimental steps described in the prior art in the art. The reagents and other instruments used are not specified by the manufacturer, and are conventional reagent products that can be obtained by purchase. In addition, the drawings are only schematic illustrations of the embodiments of the present disclosure, and are not necessarily drawn to scale. The same reference numerals in the drawings represent the same or similar parts, and thus repeated description thereof will be omitted. Some block diagrams shown in the drawings are functional entities, and do not necessarily correspond to physically or logically independent entities.

[0038] In a first aspect, the present application provides a copper-aluminum catalyst, which is an oxide formed by Cu, Al and an auxiliary metal; the auxiliary metal is a divalent auxiliary metal and / or a trivalent auxiliary metal; the divalent auxiliary metal is one or more of Mg, Zn, Ni, Ca and Co, and the trivalent auxiliary metal is one or more of Cr, Y, La and Fe;

[0039] The ratio of the total moles of the Cu and the divalent auxiliary metal to the total moles of the Al and the trivalent auxiliary metal is 3:1 to 1:3; the Cu accounts for more than 60% of the total amount of substance of the Cu and the divalent auxiliary metal, and the Al accounts for more than 80% of the total amount of substance of the Al and the trivalent auxiliary metal.

[0040] The specific surface area of the copper-aluminum catalyst is 90 m 2 / g to 120 m 2 / g.

[0041] The copper-aluminum catalyst provided in the embodiments of the present application improves the stability and catalytic activity in the following two aspects. On the one hand, the introduction of the auxiliary metal changes the spatial structure of the copper-aluminum catalyst, controls the release rate of copper during use of the copper-aluminum catalyst, slows down the deactivation caused by the agglomeration and sintering of the released copper, and thus improves the stability and catalytic activity of the copper-aluminum catalyst. On the other hand, since the copper-aluminum catalyst does not introduce a carrier, it has no complex pore structure and a relatively small specific surface area, and has a small adsorption effect on aromatic by-products, which to some extent reduces the poisoning and deactivation of the catalyst, and thus improves the stability and catalytic activity of the copper-aluminum catalyst. The copper-aluminum catalyst provided in the embodiments of the present application has high stability and catalytic activity for the synthesis of indole under high-temperature conditions (300 ℃), and the indole yield can be maintained at more than 50% after 200 h of reaction under high-temperature conditions (300 ℃), which has good industrial application prospects.

[0042] In the embodiments, the Cu and the Al in the copper-aluminum catalyst form a certain structure in a certain ratio (the total mole ratio of Cu to Al is 3:1 to 1:3); the divalent auxiliary metal replaces part of the Cu in the certain structure, regulates the spatial structure of the copper-aluminum catalyst, controls the release rate of copper during use of the copper-aluminum catalyst, slows down the deactivation caused by the agglomeration and sintering of the released copper, and thus improves the catalytic activity of the copper-aluminum catalyst; the trivalent auxiliary metal replaces part of the Al in the certain structure, regulates the spatial structure of the copper-aluminum catalyst, controls the release rate of copper during use of the copper-aluminum catalyst, slows down the deactivation caused by the agglomeration and sintering of the released copper, and thus improves the catalytic activity of the copper-aluminum catalyst; after the replacement, the Cu accounts for more than 60% of the total amount of substance of the Cu and the divalent auxiliary metal, and the Al accounts for more than 80% of the total amount of substance of the Al and the trivalent auxiliary metal.

[0043] In some embodiments of the present application, the copper-aluminum catalyst further comprises Mg;

[0044] The total moles of the Mg, the Cu and the divalent auxiliary metal to the total moles of the Al and the trivalent auxiliary metal are in a ratio of 3:1-1:3; the Mg accounts for more than 30% of the total amount of substance of the Mg, the Cu and the divalent auxiliary metal.

[0045] In the present embodiment, on the basis of the replacement of the divalent auxiliary metal and / or the trivalent auxiliary metal, the Mg also replaces part of the Cu in a certain structure, further regulates the spatial structure of the copper-aluminum catalyst and thus controls the release rate of copper in the copper-aluminum catalyst in use, slows down the deactivation caused by the agglomeration and sintering of the released copper. On the other hand, since part of the Mg enters the structure, the distribution of cations in the structure is changed, the surface properties of the catalyst are changed, and the reaction is more conducive to proceeding. Thus, the stability and catalytic activity of the copper-aluminum catalyst are further improved.

[0046] In some embodiments of the present application, the auxiliary metal is a divalent auxiliary metal and a trivalent auxiliary metal, the divalent auxiliary metal is Ca, and the trivalent auxiliary metal is Y;

[0047] The total mole ratio of the Mg, the Cu, the divalent auxiliary metal to the Al and the trivalent auxiliary metal is 1:2; the Cu accounts for 60% of the total amount of substance of the Mg, the Cu and the divalent auxiliary metal, the Mg accounts for 30% of the total amount of substance of the Mg, the Cu and the divalent auxiliary metal, and the Al accounts for 90% of the total amount of substance of the Al and the trivalent auxiliary metal.

[0048] The copper-aluminum catalyst provided in the present embodiment has the highest stability and catalytic activity for synthesizing indole under high-temperature conditions, and the indole yield can be maintained at 60.7% at 200 h of reaction.

[0049] In a second aspect, the present application provides a preparation method of the copper-aluminum catalyst described in the first aspect, which is used for synthesizing indole, and the preparation method comprises:

[0050] S1, uniformly mixing a Cu source, an Al source and an auxiliary metal source, and then placing them in a ball mill jar for ball milling, and then drying to obtain a catalyst precursor; the auxiliary metal source is a divalent auxiliary metal source and / or a trivalent auxiliary metal source; the divalent auxiliary metal source is one or more of Mg, Zn, Ni, Ca and Co sources, and the trivalent auxiliary metal source is one or more of Cr, Y, La and Fe sources;

[0051] S2, the catalyst precursor is ground and placed in an air or oxygen atmosphere, and calcined at 800-1200 DEG C for 1-6 hours to obtain a copper-aluminum catalyst.

[0052] Specifically, the divalent auxiliary metal source is one or more of oxides, hydroxides, and acetates of Mg, Zn, Ni, Ca, and Co, and the trivalent auxiliary metal source is one or more of oxides, hydroxides, and acetates of Cr, Y, La, and Fe.

[0053] In the embodiments of the present application, a solid-liquid ball milling method is used to obtain a catalyst precursor, and the catalyst precursor is calcined at high temperature to undergo an oxidation reaction, so as to obtain oxides formed by Cu, Al, and auxiliary metals.

[0054] The preparation method provided by the present application is simple, easy to operate, low in cost, and green and environmentally friendly, without generating three wastes during the entire preparation process. Specifically, since nitrate is not used as the Cu source, the Al source, or the auxiliary metal source, no waste gas or waste liquid is generated during the entire preparation process, and the method is green and environmentally friendly.

[0055] In some embodiments of the present application, the Cu source, the Al source, and the auxiliary metal source are uniformly mixed, and the mixing includes:

[0056] The Cu source, the Al source, and the auxiliary metal source are uniformly mixed in a solvent; and the solvent is a mixture including polyethylene glycol.

[0057] In some embodiments of the present application, the Cu source is one or more of copper oxide, copper hydroxide, and copper acetate, the Al source is one or more of aluminum oxide, aluminum hydroxide, and pseudo-boehmite, and the solvent is a mixture of polyethylene glycol and deionized water in a mass ratio of 0.1-6:100.

[0058] In the embodiments, since nitrate is not used as the Cu source or the Al source, no waste gas is generated during the entire preparation process, and the method is green and environmentally friendly; if nitrate is used as the Cu source, the Al source, or the auxiliary metal source, toxic gases such as nitric oxide and nitrogen dioxide are generated.

[0059] In the embodiments, the preparation process of the solvent is as follows: 0.1-6 % of polyethylene glycol based on the mass of deionized water is added to the deionized water and heated until completely dissolved, and the obtained mixture of deionized water and polyethylene glycol is used as the solvent; and the polyethylene glycol is one or more of PEG-600, PEG-800, PEG-1000, and PEG-1500.

[0060] In the prior art, the solvent commonly used in ball milling in the preparation of the catalyst is a mixture of water and ethanol. In the embodiment, the various solid body compounds, i.e. the Cu source, the Al source and the additive metal source, are more uniformly dispersed by adding polyethylene glycol, so that the performance of the catalyst is improved to a certain extent. In addition, since ethanol is not used as the solvent in the embodiment, no waste liquid is generated in the entire preparation process, and the process has the characteristics of green and no pollution.

[0061] In some embodiments of the application, the ball milling process is as follows: zirconium balls with a diameter of 5 mm to 10 mm are added, and the ball milling is performed at a rotation speed of 200 r / min to 800 r / min for 2 h to 15 h.

[0062] The process parameters for the drying are as follows: drying at a temperature of 80 ℃ to 150 ℃ for 5 h to 24 h.

[0063] In some embodiments of the application, the Mg source is simultaneously mixed with the Cu source, the Al source and the additive metal source in the process of uniformly mixing the Cu source, the Al source and the additive metal source. The Mg source is one or more of magnesium oxide, magnesium hydroxide and magnesium acetate.

[0064] In the embodiment, on the basis of the replacement of the divalent additive metal and / or the trivalent additive metal, the Mg also replaces part of the Cu in a certain structure, so that the spatial structure of the copper-aluminum catalyst is further regulated, the release rate of copper in the copper-aluminum catalyst in use is controlled, the deactivation caused by the agglomeration and sintering of the released copper is slowed down, and the catalytic activity of the copper-aluminum catalyst is further improved.

[0065] In a third aspect, the application provides an application of the copper-aluminum catalyst. The copper-aluminum catalyst described in the first aspect is used in the reaction of synthesizing an indole compound or an indole derivative by the alcohol amine method.

[0066] The principle of synthesizing indole based on the alcohol amine method is different from the principle of synthesizing indole by other methods, so the copper-aluminum catalyst provided by the application is only used for synthesizing indole from aniline and ethylene glycol. The copper-aluminum catalyst is used in the synthesis of indole compounds and can also be used in the preparation of indole derivatives.

[0067] The copper-aluminum catalyst provided in the embodiments of the application has high stability and catalytic activity for the synthesis of indole under high temperature conditions, and the indole yield can be maintained at more than 50 % at 200 h of reaction, which has good industrial application prospects.

[0068] In some embodiments of the application, the application includes:

[0069] The aniline and the ethylene glycol are reacted directly using the copper-aluminum catalyst under the conditions of continuously passing hydrogen, a reaction temperature of 260 ℃-350 ℃, a space velocity of 0.1 h -1 ~3.0 h -1 to obtain an indole compound or an indole derivative; wherein the molar ratio of the aniline and the ethylene glycol is 1:1-9:1.

[0070] In the prior art, the prepared catalyst is pre-reduced by passing hydrogen before being used as a catalyst for synthesizing indole by the alcohol amine method, so that all the active copper is released, thereby the active copper can promote the reaction of aniline and ethylene glycol. However, the release of all the active copper is prone to cause copper agglomeration and sintering, resulting in a sharp deactivation of the catalytic activity.

[0071] The copper-aluminum catalyst obtained by the method provided by the present application does not need to be pre-reduced before use, which simplifies the application steps. In addition, the stability of the copper-aluminum catalyst is improved, so that the present embodiment can avoid the agglomeration and sintering of the active copper during the synthesis of indole, and further, the active copper that does not agglomerate and sinter improves the catalytic activity of the copper-aluminum catalyst to a certain extent.

[0072] Specifically, the copper-aluminum catalyst obtained by the preparation method provided by the present application has a stable structure. The addition of the auxiliary metal and magnesium in the copper-aluminum catalyst improves the stability of the copper-aluminum catalyst. Further, in the gas phase reaction process of aniline and ethylene glycol, the copper in the form of copper oxide in the stable structure is reduced to active copper slowly under the hydrogen atmosphere. The addition of the auxiliary metal and magnesium controls the release rate of copper to a certain extent, slows down the deactivation caused by the agglomeration and sintering of the released copper, and thus improves the catalytic activity of the copper-aluminum catalyst.

[0073] In a fourth aspect, the present application provides a regeneration method of the copper-aluminum catalyst. The copper-aluminum catalyst after being applied according to the third aspect is regenerated by in-situ air roasting.

[0074] The copper-aluminum catalyst provided by the embodiments of the present application has regenerability. The copper-aluminum catalyst is applied to the reaction of synthesizing an indole compound or an indole derivative. After the reaction is completed, the used and inactive copper-aluminum catalyst is regenerated by a simple roasting method. The catalytic performance of the regenerated copper-aluminum catalyst is equivalent to that of the newly prepared copper-aluminum catalyst.

[0075] In some embodiments of the present application, the regeneration process of the copper-aluminum catalyst is as follows:

[0076] Air or oxygen-containing nitrogen is passed into the reactor at a gas space velocity of 50 h -1 ~1000 h-1 The copper-aluminum catalyst after the reaction is heated and kept at in-situ for 15 h to 20 h at a heating rate of 0.1 ℃ / min to 0.5 ℃ / min until the temperature reaches 200 ℃ to 400 ℃, and a regenerated copper-aluminum catalyst is obtained, which is reused in the reaction for synthesizing indole compounds or indole derivatives.

[0077] In order for those skilled in the art to better understand the present application, the preparation method provided by the present application is described below through a plurality of specific examples.

[0078] Comparative Example 1

[0079] 9.76 g of copper hydroxide [Cu(OH)2] and 15.6 g of aluminum hydroxide [Al(OH)3] were mixed and stirred to obtain a mixture; 80 mL of deionized water was weighed and added to the above mixture, and after stirring and mixing uniformly, it was placed in a ball mill tank, 200 mL of zirconium balls with a diameter of 10 mm were added, and ball milling was carried out at a speed of 300 r / min for 2 h; the sample after ball milling was dried at 100 ℃ for 16 h to obtain a catalyst precursor.

[0080] The catalyst precursor was transferred to a muffle furnace and heated to 1000 ℃ at a heating rate of 5 ℃ / min under an air atmosphere, and calcination was carried out for 3 h to obtain a catalyst, and the specific surface area of the catalyst was 101.2556 m 2 / g.

[0081] Application of the catalyst: 1.5 g of the obtained catalyst was loaded into a reactor, heated to 300 ℃, and the reaction was started. The molar ratio of ethylene glycol to aniline was 1:7, and the space velocity was 0.5 h -1 . The evaluation conditions and results are shown in Table 1.

[0082] Comparative Example 2

[0083] 5.86 g of copper hydroxide [Cu(OH)2], 2.33 g of magnesium hydroxide [Mg(OH)2] and 15.6 g of aluminum hydroxide [Al(OH)3] were mixed and stirred to obtain a mixture; 80 mL of deionized water was weighed and added to the above mixture, and after stirring and mixing uniformly, it was placed in a ball mill tank, 200 mL of zirconium balls with a diameter of 10 mm were added, and ball milling was carried out at a speed of 300 r / min for 2 h; the sample after ball milling was dried at 100 ℃ for 16 h to obtain a catalyst precursor.

[0084] The catalyst precursor was transferred to a muffle furnace and heated to 1000 ℃ at a heating rate of 5 ℃ / min under an air atmosphere, and calcination was carried out for 3 h to obtain a catalyst, and the specific surface area of the catalyst was 102.1229 m 2 / g.

[0085] Application of the catalyst: 1.5 g of the obtained catalyst was loaded into a reactor, heated to 300 ℃, and the feeding reaction was started with a molar ratio of ethylene glycol to aniline of 1:7 and a space velocity of 0.5 h -1 . The evaluation conditions and results are shown in Table 1.

[0086] Example 1

[0087] 5.86 g of copper hydroxide [Cu(OH)2], 1.75 g of magnesium hydroxide [Mg(OH)2], 0.99 g of zinc hydroxide [Zn(OH)2], and 15.6 g of aluminum hydroxide [Al(OH)3] were mixed and stirred to obtain a mixture; 80 mL of deionized water was weighed, 2.4 g of polyethylene glycol PEG-600 was added and heated to 80 ℃ to completely dissolve, and then added to the above mixture, and after stirring and mixing uniformly, placed in a ball mill tank, and then 200 mL of zirconium balls with a diameter of 10 mm were added, and ball milled at a speed of 300 r / min for 2 h; the sample after ball milling was dried at 100 ℃ for 16 h to obtain a catalyst precursor.

[0088] The catalyst precursor was transferred to a muffle furnace and heated to 1000 ℃ at a heating rate of 5 ℃ / min under an air atmosphere, and calcined for 3 h to obtain a copper-magnesium-aluminum catalyst, and the specific surface area of the copper-magnesium-aluminum catalyst was 99.0622 m 2 / g.

[0089] Application of the copper-magnesium-aluminum catalyst: 1.5 g of the obtained copper-magnesium-aluminum catalyst was loaded into a reactor, heated to 300 ℃, and the feeding reaction was started with a molar ratio of ethylene glycol to aniline of 1:7 and a space velocity of 0.5 h -1 . The evaluation conditions and results are shown in Table 1.

[0090] Example 2

[0091] 5.86 g of copper hydroxide [Cu(OH)2], 2.33 g of magnesium hydroxide [Mg(OH)2], and 14.04 g of aluminum hydroxide [Al(OH)3], and 3.8 g of lanthanum hydroxide [La(OH)3] were mixed and stirred to obtain a mixture; 80 mL of deionized water was weighed, 2.4 g of polyethylene glycol PEG-600 was added and heated to 80 ℃ to completely dissolve, and then added to the above mixture, and after stirring and mixing uniformly, placed in a ball mill tank, and then 200 mL of zirconium balls with a diameter of 10 mm were added, and ball milled at a speed of 300 r / min for 2 h; the sample after ball milling was dried at 100 ℃ for 16 h to obtain a catalyst precursor.

[0092] The catalyst precursor was transferred to a muffle furnace, heated to 1000 ℃ at a heating rate of 5 ℃ / min under an air atmosphere, calcined for 3 h, to obtain a copper-magnesium-aluminum catalyst, the specific surface area of the copper-magnesium-aluminum catalyst being 103.6954 m 2 / g.

[0093] Application of the copper-magnesium-aluminum catalyst: 1.5 g of the obtained copper-magnesium-aluminum catalyst was loaded into a reactor, heated to 300 ℃, and the feeding reaction was started, the molar ratio of ethylene glycol to aniline being 1:7, the space velocity being 0.5 h -1 The evaluation conditions and results are shown in Table 1.

[0094] Example 3

[0095] 5.86 g of copper hydroxide [Cu(OH)2], 1.75 g of magnesium hydroxide [Mg(OH)2], 0.74 g of calcium hydroxide [Ca(OH)2], 14.04 g of aluminum hydroxide [Al(OH)3], and 2.8 g of yttrium hydroxide [Y(OH)3] were mixed and stirred to obtain a mixture; 80 mL of deionized water was weighed, 2.4 g of polyethylene glycol PEG-600 was added, heated to 80 ℃ to completely dissolve, and then added to the above mixture, and after stirring and mixing uniformly, placed in a ball mill tank, 200 mL of zirconium balls with a diameter of 10 mm was added, and ball milled at a speed of 300 r / min for 2 h; the sample after ball milling was dried at 100 ℃ for 16 h. The catalyst precursor was obtained.

[0096] The catalyst precursor was transferred to a muffle furnace, heated to 1000 ℃ at a heating rate of 5 ℃ / min under an air atmosphere, calcined for 3 h, to obtain a copper-magnesium-aluminum catalyst, the specific surface area of the copper-magnesium-aluminum catalyst being 105.2349 m 2 / g.

[0097] Application of the copper-magnesium-aluminum catalyst: 1.5 g of the obtained copper-magnesium-aluminum catalyst was loaded into a reactor, heated to 300 ℃, and the feeding reaction was started, the molar ratio of ethylene glycol to aniline being 1:7, the space velocity being 0.5 h -1 The evaluation conditions and results are shown in Table 1.

[0098] Example 4

[0099] Mixing and stirring 5.86 g of copper hydroxide [Cu(OH)2], 1.75 g of magnesium hydroxide [Mg(OH)2], 0.74 g of calcium hydroxide [Ca(OH)2] and 14.04 g of aluminum hydroxide [Al(OH)3], 2.8 g of yttrium hydroxide [Y(OH)3] to obtain a mixture; weigh 80 mL of deionized water, add 2.4 g of polyethylene glycol PEG-800 to heat to 80 ℃ to completely dissolve, then add the above mixture, stir and mix uniformly, then place in a ball mill tank, add 200 mL of zirconium balls with a diameter of 10 mm, and ball mill at a speed of 300 r / min for 2 h; the sample after ball milling is dried at 100 ℃ for 16 h to obtain a catalyst precursor.

[0100] Transfer the catalyst precursor to a muffle furnace, heat to 1000 ℃ at a heating rate of 5 ℃ / min under an air atmosphere, and calcine for 3 h to obtain a copper-magnesium-aluminum catalyst, the specific surface area of the copper-magnesium-aluminum catalyst being 96.8756 m 2 / g.

[0101] As Figure 2 shown in FIG. 5 is a scanning electron microscope image of the copper-magnesium-aluminum catalyst of this example, and Figure 3 FIG. 6 shows the pore size distribution of the copper-magnesium-aluminum catalyst of this example.

[0102] Application of the copper-magnesium-aluminum catalyst: 1.5 g of the obtained copper-magnesium-aluminum catalyst is loaded into a reactor, heated to 300 ℃, and the feeding reaction is started, the molar ratio of ethylene glycol to aniline being 1:7, and the space velocity being 0.5 h -1 . The evaluation conditions and results are shown in Table 1.

[0103] Example 5

[0104] Mixing and stirring 5.86 g of copper hydroxide [Cu(OH)2], 1.75 g of magnesium hydroxide [Mg(OH)2], 0.74 g of calcium hydroxide [Ca(OH)2] and 14.04 g of aluminum hydroxide [Al(OH)3], 2.8 g of yttrium hydroxide [Y(OH)3] to obtain a mixture; weigh 80 mL of deionized water, add 2.4 g of polyethylene glycol PEG-800 to heat to 80 ℃ to completely dissolve, then add the above mixture, stir and mix uniformly, then place in a ball mill tank, add 200 mL of zirconium balls with a diameter of 10 mm, and ball mill at a speed of 300 r / min for 2 h; the sample after ball milling is dried at 100 ℃ for 16 h to obtain a catalyst precursor.

[0105] Transfer the catalyst precursor to a muffle furnace, heat to 1000 ℃ at a heating rate of 5 ℃ / min under an air atmosphere, and calcine for 3 h to obtain a copper-magnesium-aluminum catalyst, the specific surface area of the copper-magnesium-aluminum catalyst being 96.8756 m 2 / g.

[0106] Application of copper-magnesium-aluminum catalyst: 1.5 g of the obtained copper-magnesium-aluminum catalyst was loaded into a reactor, heated to 300°C, and the feeding reaction was started, the molar ratio of ethylene glycol to aniline was 1:7, and the space velocity was 0.5 h -1 . The evaluation conditions and results are shown in Table 1.

[0107] Example 6

[0108] 5.86 g of copper hydroxide [Cu(OH)2], 1.75 g of magnesium hydroxide [Mg(OH)2], 0.74 g of calcium hydroxide [Ca(OH)2], and 14.04 g of aluminum hydroxide [Al(OH)3], 2.8 g of yttrium hydroxide [Y(OH)3] were mixed and stirred to obtain a mixture; 80 mL of deionized water was weighed, 2.4 g of polyethylene glycol PEG-1500 was added and heated to 80°C to completely dissolve, then added to the above mixture, and stirred and mixed uniformly, then placed in a ball mill tank, 200 mL of zirconium balls with a diameter of 10 mm were added, and ball milling was carried out at a speed of 300 r / min for 2 h; the sample after ball milling was dried at 100°C for 16 h to obtain a catalyst precursor.

[0109] The catalyst precursor was transferred to a muffle furnace and heated to 800°C at a heating rate of 5°C / min under an air atmosphere, and calcined for 1 h to obtain a copper-magnesium-aluminum catalyst, the specific surface area of the copper-magnesium-aluminum catalyst was 100.2365 m 2 / g.

[0110] Application of copper-magnesium-aluminum catalyst: 1.5 g of the obtained copper-magnesium-aluminum catalyst was loaded into a reactor, heated to 300°C, and the feeding reaction was started, the molar ratio of ethylene glycol to aniline was 1:7, and the space velocity was 0.5 h -1 . The evaluation conditions and results are shown in Table 1.

[0111] Example 7

[0112] 5.86 g of copper hydroxide [Cu(OH)2], 1.75 g of magnesium hydroxide [Mg(OH)2], 0.74 g of calcium hydroxide [Ca(OH)2], and 14.04 g of aluminum hydroxide [Al(OH)3], 2.8 g of yttrium hydroxide [Y(OH)3] were mixed and stirred to obtain a mixture; 80 mL of deionized water was weighed, 2.4 g of polyethylene glycol PEG-1000 was added and heated to 80°C to completely dissolve, then added to the above mixture, and stirred and mixed uniformly, then placed in a ball mill tank, 200 mL of zirconium balls with a diameter of 10 mm were added, and ball milling was carried out at a speed of 300 r / min for 2 h; the sample after ball milling was dried at 100°C for 16 h to obtain a catalyst precursor.

[0113] The catalyst precursor was transferred to a muffle furnace, heated to 1200 ℃ at a heating rate of 5 ℃ / min under an air atmosphere, calcined for 6 h, to obtain a copper-magnesium-aluminum catalyst, the specific surface area of the copper-magnesium-aluminum catalyst being 102.3634 m 2 / g.

[0114] Application of the copper-magnesium-aluminum catalyst: 1.5 g of the obtained copper-magnesium-aluminum catalyst was loaded into a reactor, heated to 300 ℃, and the feeding reaction was started, the molar ratio of ethylene glycol to aniline being 1:7, and the space velocity being 0.5 h -1 . The evaluation conditions and results are shown in Table 1.

[0115] Example 8

[0116] 5.86 g of copper hydroxide [Cu(OH)2], 1.75 g of magnesium hydroxide [Mg(OH)2], 0.93 g of cobalt hydroxide [Co(OH)2], and 18.72 g of aluminum hydroxide [Al(OH)3], 6.18 g of chromium hydroxide [Cr(OH)3] were mixed and stirred to obtain a mixture; 80 mL of deionized water was weighed, 2.4 g of polyethylene glycol PEG-1000 was added, heated to 80 ℃ to completely dissolve, and then added to the above mixture, and after stirring and mixing uniformly, placed in a ball mill tank, 200 mL of zirconium balls with a diameter of 10 mm were added, and ball milled at a speed of 300 r / min for 2 h; the sample after ball milling was dried at 100 ℃ for 16 h to obtain a catalyst precursor.

[0117] The catalyst precursor was transferred to a muffle furnace, heated to 1200 ℃ at a heating rate of 5 ℃ / min under an air atmosphere, calcined for 6 h, to obtain a copper-magnesium-aluminum catalyst, the specific surface area of the copper-magnesium-aluminum catalyst being 108.3658 m 2 / g.

[0118] Application of the copper-magnesium-aluminum catalyst: 1.5 g of the obtained copper-magnesium-aluminum catalyst was loaded into a reactor, heated to 300 ℃, and the feeding reaction was started, the molar ratio of ethylene glycol to aniline being 1:7, and the space velocity being 0.5 h -1 . The evaluation conditions and results are shown in Table 1.

[0119] Example 9

[0120] Mixing and stirring 5.86 g of copper hydroxide [Cu(OH)2], 1.75 g of magnesium hydroxide [Mg(OH)2], 0.93 g of cobalt hydroxide [Co(OH)2] and 6.24 g of aluminum hydroxide [Al(OH)3], 2.06 g of chromium hydroxide [Cr(OH)3] to obtain a mixture; weigh 80 mL of deionized water, add 2.4 g of polyethylene glycol PEG-1000, heat to 80 ℃ to completely dissolve, then add the above mixture, stir and mix uniformly, then place in a ball mill tank, add 200 mL of zirconium balls with a diameter of 10 mm, and ball mill at a speed of 300 r / min for 2 h; the sample after ball milling is dried at 100 ℃ for 16 h to obtain a catalyst precursor.

[0121] The catalyst precursor is transferred to a muffle furnace and heated to 1200 ℃ at a heating rate of 5 ℃ / min under an air atmosphere, and calcined for 6 h to obtain a copper-magnesium-aluminum catalyst, the specific surface area of the copper-magnesium-aluminum catalyst is 99.6237 m 2 / g.

[0122] Application of the copper-magnesium-aluminum catalyst: 1.5 g of the obtained copper-magnesium-aluminum catalyst is loaded into a reactor, heated to 300 ℃, and the feeding reaction is started, the molar ratio of ethylene glycol to aniline is 1:7, and the space velocity is 0.5 h -1 . The evaluation conditions and results are shown in Table 1.

[0123] Example 10

[0124] Mixing and stirring 5.86 g of copper hydroxide [Cu(OH)2], 1.75 g of magnesium hydroxide [Mg(OH)2], 0.93 g of cobalt hydroxide [Co(OH)2] and 6.24 g of aluminum hydroxide [Al(OH)3], 2.06 g of chromium hydroxide [Cr(OH)3] to obtain a mixture; weigh 80 mL of deionized water, add 2.4 g of polyethylene glycol PEG-1000, heat to 80 ℃ to completely dissolve, then add the above mixture, stir and mix uniformly, then place in a ball mill tank, add 200 mL of zirconium balls with a diameter of 10 mm, and ball mill at a speed of 300 r / min for 2 h; the sample after ball milling is dried at 100 ℃ for 16 h to obtain a catalyst precursor.

[0125] The catalyst precursor is transferred to a muffle furnace and heated to 1200 ℃ at a heating rate of 5 ℃ / min under an air atmosphere, and calcined for 6 h to obtain a copper-magnesium-aluminum catalyst, the specific surface area of the copper-magnesium-aluminum catalyst is 99.6237 m 2 / g.

[0126] Application of copper-magnesium-aluminum catalyst: 1.5 g of the obtained copper-magnesium-aluminum catalyst was loaded into a reactor, heated to 300°C, and the reaction was started. The molar ratio of ethylene glycol to aniline was 1:7, and the space velocity was 0.5 h -1 . The evaluation conditions and results are shown in Table 1.

[0127] Table 1 Evaluation conditions and results of examples and comparative examples

[0128]

[0129] Example 11

[0130] Mix 5.86 g of copper hydroxide [Cu(OH)2], 1.75 g of magnesium hydroxide [Mg(OH)2], 0.74 g of calcium hydroxide [Ca(OH)2], and 14.04 g of aluminum hydroxide [Al(OH)3], 2.8 g of yttrium hydroxide [Y(OH)3] and stir to obtain a mixture; weigh 80 mL of deionized water, add 2.4 g of polyethylene glycol PEG-1000, heat to 80°C to completely dissolve, then add the above mixture, stir to mix uniformly, and then place in a ball mill tank. Add 200 mL of zirconium balls with a diameter of 10 mm, and ball mill at a speed of 300 r / min for 2 h. The sample after ball milling was dried at 100°C for 16 h to obtain a catalyst precursor.

[0131] The catalyst precursor was transferred to a muffle furnace and heated to 1000°C at a heating rate of 5°C / min under an air atmosphere, and calcined for 3 h to obtain a copper-magnesium-aluminum catalyst. The specific surface area of the copper-magnesium-aluminum catalyst was 99.8957 m 2 / g.

[0132] Application of copper-magnesium-aluminum catalyst: 1.5 g of the obtained copper-magnesium-aluminum catalyst was loaded into a reactor, heated to 280°C, and the reaction was started. The molar ratio of ethylene glycol to aniline was 1:7, and the space velocity was 0.5 h -1 . The evaluation conditions and results are shown in Table 1.

[0133] Example 12

[0134] Mixing and stirring 5.86 g copper hydroxide [Cu(OH)2], 1.75 g magnesium hydroxide [Mg(OH)2], 0.74 g calcium hydroxide [Ca(OH)2] and 14.04 g aluminum hydroxide [Al(OH)3], 2.8 g yttrium hydroxide [Y(OH)3] to obtain a mixture; weighing 80 mL of deionized water, adding 2.4 g of polyethylene glycol PEG-1000 to heat to 80 ℃ to completely dissolve, then adding the above mixture, stirring and mixing uniformly, then placing in a ball mill tank, adding 200 mL of zirconium balls with a diameter of 10 mm, and ball milling at a speed of 300 r / min for 2 h; the sample after ball milling is dried at 100 ℃ for 16 h to obtain a catalyst precursor.

[0135] The catalyst precursor is transferred to a muffle furnace and heated to 1000 ℃ at a heating rate of 5 ℃ / min under an air atmosphere, and calcined for 3 h to obtain a copper-magnesium-aluminum catalyst, the specific surface area of the copper-magnesium-aluminum catalyst is 109.1894 m 2 / g.

[0136] Application of the copper-magnesium-aluminum catalyst: 1.5 g of the obtained copper-magnesium-aluminum catalyst is loaded into a reactor, heated to 350 ℃, and the feeding reaction is started, the molar ratio of ethylene glycol to aniline is 1:7, and the space velocity is 0.5 h -1 . The evaluation conditions and results are shown in Table 1.

[0137] Example 13

[0138] Based on the copper-magnesium-aluminum catalyst prepared in Example 4, the catalyst deactivation and regeneration method is described. When the activity of the copper-magnesium-aluminum catalyst in the synthesis of indole decreases to less than 40 % of the reaction yield, the copper-magnesium-aluminum catalyst is regenerated in situ, and the regeneration process is as follows: air is introduced into the reactor at a space velocity of 100 h -1 , and the temperature is raised to 300 ℃ at a heating rate of 0.15 ℃ / min, and the temperature is kept for 20 h, and the regeneration is completed.

[0139] The regenerated copper-magnesium-aluminum catalyst is used for the synthesis of indole from ethylene glycol and aniline according to the application process of the copper-magnesium-aluminum catalyst shown in Example 4.

[0140] After in-situ regeneration, the reaction effect of the regenerated catalyst is compared and tested, and the specific results are as follows: after regeneration for 1 time, the indole yield is 59.1 % after 200 h of testing; after regeneration for 2 times, the indole yield is 58.6 % after 200 h of testing.

[0141] Example 14

[0142] In the present embodiment, compared with the embodiment 13, the temperature is raised at 2 ℃ / min, after the first regeneration, the indole yield is 32.7% after 200 h test; in the same way, after the second regeneration, the indole yield is 21.5% after 200 h test. This is because in order to ensure that the catalyst has a high yield of indole synthesis after regeneration, it is necessary to ensure that the carbon deposited on the used catalyst can be fully removed, and the original microstructure of the catalyst is not damaged, and it is necessary to ensure slow heating to fully remove the residual in each small pore of the catalyst.

[0143] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in the specification.

[0144] For the method embodiments, for the sake of simple description, they are all expressed as a combination of a series of actions, but those skilled in the art should know that the present application is not limited by the order of the described actions, because according to the present application, certain steps can be performed in other order or simultaneously. Secondly, those skilled in the art should know that the embodiments described in the specification are all preferred embodiments, and the actions and components involved are not necessarily necessary for the present application.

[0145] The above describes in detail the copper-aluminum catalyst, the preparation method, the application and the regeneration method thereof provided by the present application. The principles and implementation modes of the present application are described by using specific examples in this paper. The above embodiment description is only used to help understand the method and core idea of the present application; at the same time, for those skilled in the art, according to the idea of the present application, the specific implementation mode and application range will be changed; in view of the above, the content of the present specification should not be understood as a limitation of the present application.

Claims

1. An application of a copper-aluminum catalyst, characterized in that, The copper-aluminum catalyst is directly used in the synthesis of indole compounds from aniline and ethylene glycol. The catalyst is used under the following conditions: hydrogen gas is introduced, the reaction temperature is 260℃~350℃, and the space velocity is 0.1 h⁻¹. -1 ~3.0 h -1 The reaction is carried out under specific conditions to obtain indole compounds; wherein the molar ratio of aniline to ethylene glycol is 1:1 to 9:

1. The copper-aluminum catalyst is an oxide formed from Cu, Al, Mg and an auxiliary metal; the auxiliary metal is a divalent auxiliary metal and a trivalent auxiliary metal, the divalent auxiliary metal is Ca and the trivalent auxiliary metal is Y; The total molar ratio of Mg, Cu, and the divalent auxiliary metal to Al and the trivalent auxiliary metal is 1:2; Cu accounts for 60% of the total mass of Mg, Cu, and the divalent auxiliary metal; Mg accounts for 30% of the total mass of Mg, Cu, and the divalent auxiliary metal; and Al accounts for 90% of the total mass of Al and the trivalent auxiliary metal. The preparation method of the copper-aluminum catalyst includes: S1, after uniformly mixing Cu source, Al source, Mg source and auxiliary metal source, the mixture is placed in a ball mill jar for ball milling, and then dried to obtain catalyst precursor; the auxiliary metal source is a divalent auxiliary metal source and a trivalent auxiliary metal source; the divalent auxiliary metal source is Ca, and the trivalent auxiliary metal source is Y; S2, the catalyst precursor is ground and then placed in an air or oxygen atmosphere and calcined at 800 ℃~1200 ℃ for 1 h~6 h to obtain a copper-aluminum catalyst; The Cu source, Al source, Mg source, and auxiliary metal source are mixed uniformly, including: The Cu source, Al source, Mg source and auxiliary metal source are mixed uniformly in a solvent; the solvent is a mixture including polyethylene glycol; The Cu source is one or more of copper oxide, copper hydroxide, and copper acetate, and the Al source is one or more of aluminum oxide, aluminum hydroxide, and boehmite. The solvent is a mixture of polyethylene glycol and deionized water in a mass ratio of 0.1 to 6:100; The Mg source is one or more of magnesium oxide, magnesium hydroxide, and magnesium acetate.

2. The application of the copper-aluminum catalyst according to claim 1, characterized in that, The ball milling process is as follows: add zircon balls with a diameter of 5 mm to 10 mm, and ball mill for 2 h to 15 h at a rotation speed of 200 r / min to 800 r / min; The drying process parameters are: drying at a temperature of 80 ℃ to 150 ℃ for 5 h to 24 h.

3. A method for regenerating a copper-aluminum catalyst, characterized in that, The copper-aluminum catalyst described in claim 1 is regenerated by in-situ gas roasting.

4. The method for regenerating the copper-aluminum catalyst according to claim 3, characterized in that, The regeneration process of the copper-aluminum catalyst is as follows; Air or nitrogen containing oxygen is introduced into the reactor at a gas space velocity of 50 h⁻¹. -1 ~1000h -1 Under certain conditions, the copper-aluminum catalyst after the reaction is heated and held in situ at a rate of 0.1 ℃ / min to 0.5 ℃ / min until it reaches 200 ℃ to 400 ℃. After holding at this temperature for 2 h to 20 h, the copper-aluminum catalyst after regeneration is obtained. The copper-aluminum catalyst is then reused in the reaction to synthesize indole compounds.

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